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The foam insulation pad under C900 carpets traps water leading to floor pan rust. The black felt paper on top of the foam prevents water from evaporating so the foam traps water when it gets inside. What is the best material to replace the foam pad insulation? I have some felted fabric material that is used for carpet underlayment. It has no felt paper cover to trap water. Is that good or is something else better? What have other forum members used? Results? Or should I just continue to use the stock foam. I have replaced the vert top and taken care of the floor plan surface rust, so now have a dry interior. Please give recommendations
 

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The foam insulation pad under C900 carpets traps water leading to floor pan rust. The black felt paper on top of the foam prevents water from evaporating so the foam traps water when it gets inside. What is the best material to replace the foam pad insulation? I have some felted fabric material that is used for carpet underlayment. It has no felt paper cover to trap water. Is that good or is something else better? What have other forum members used? Results? Or should I just continue to use the stock foam. I have replaced the vert top and taken care of the floor plan surface rust, so now have a dry interior. Please give recommendations
I think the original stuff works really well unless you have a swimming pool for a floor. It stops moisture getting to the floor as well as holding it there when you do have a leak.

I don't have any leaks and my floors are fine. Goes with anything, liner or not, if it's wet for a long time it will probably rust. With normal moisture here and there it won't. But if you put a more porous liner in there and you have wet /snow laden feet all the time the moisture may get through to the floor pans as well..

It's a double edged sword to me.
 

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I've seen folks write about Dynamax and/or Dynamat sound deadening material for use under the carpet. Haven't used it myself. The original material is often referred to as a 'floor ruster' for its ability to kill floors. Best of luck!
 

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For my Charade which I wanted to do to make it more refined as it was a bit noisy I went to my "Wickes" store (a more traditional DIY store - no other junk apart from materials/fixings etc) and got self adhesive house/shed roof liner material, the rubberish type of stuff, it's more of a sound deadener really and it's supposed to be almost the same as the Dynamat stuff.
Anyway it's still on and still doing it's job, being as it is roofing material I would've thought it'd be useful
 

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I think the factory underpayment did a good job for a reasonable amount of time, but after 20+ years, I don't know of any type of insulation that will stand up to that kind of service unscathed. The only rust on my whole car was under the drivers side carpeting. I've media blasted, primed and repainted the area and luckily, it was basically surface rust. I have a parts vert and as luck would have it, the floor is mint. I took the underpayment (not so mint, but better than mine) out of it and put it in my driver, but I'm looking at alternatives to the factory stuff too. That Dynamat stuff is pretty impressive as far as sound dampening, but I think you'd need some kind of insulation from heat as well. I was thinking maybe Rhino liner on the floor pan and then get some quality automotive insulation to lay between that and the carpet. Car audio places carry good insulation. I might do some checking to see if I can find out what they use.
 

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earlier cars used to use the felt type sound deadener some cars just had bare carpets, it is one of the probs with the rubber/sponge that once water ingress occurs they is virtually no way the water can get out, as I have broken a few cars in my time and the carpets are dry etc but you remove the carpet to get at bits tec and you usually seem to find one sponge that has 'some' water in it and usually it stinjs so it;';s been there a long time, and the last one I dismantled,. me and STEVE Z found one which had a tar/water mix soaked in it.
 

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As Alwyne says when we broke one few weeks back at his the drivers one was wet, as was mine, and the rear too. Front had oil in too, probably power steering that one but the scrappy one was in better condition, but guess who forgot to take it back with him!!
Damn thing got wet again cos of swapping doors and leaving rubber seal off the door so I could repair it, damn British weather at it again, beginning to think I was in a boat the amount of bailing I had to do.
I'm still keeping with the sponge though, I'm gonna seal all the leaks if it's the last thing I'm gonna do and with it being dry it would appear to do a good job
 
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